( xxiv ) 



fact, we are not acquainted with the full life history of this 

 insect, not knowing how many generations appear in the year, 

 or whether the mating is accomplished in the fall before 

 hibernation, or in the spring after hibernation, so one cannot 

 be sure that the case substantiates your suggested theory of 

 gregarious hibernation as a means for quick mating in the 

 spring. 



" A third familiar example of * sembling ' to be noted in 

 California is the gathering in great numbers of the butterfly, 

 Pyranieis cardui, repeatedly observed in Southern California 

 near Claremont village." 



The President then read a short paper bearing on the same 

 subject, entitled " A possible explanation of insect swarms 

 on mountain-tops." The speaker said that he had been led 

 to make this communication in consequence of Mr. G. C. 

 Champion's exhibit at the last meeting of Dorcadion from 

 Spanish mountain-tops. These specimens and the description 

 of Coccinellidae, on the summits revived the speaker's memories 

 of his visit to the Sierra Guadarrama in July 1902, and of tlie 

 hypothesis which had suggested itself as an explanation of the 

 similar and kindred phenomena which had come under his 

 observation. On an isolated mass of rock near the summit of 

 Peiialara (about 7700 feet), behind La Granja (San Ildefonso), 

 he had found, on July 25, 1902, Coccinella 7-punctata under 

 every stone, Dorcadion hispanicum crawling about every- 

 where, and Ammophila hirsuta fliying in a swarm. The latter 

 it will be remembered was found by Fabre in hundreds under 

 a flat stone on the summit of Mont Ventoux, on a cold rainy 

 day. Fabre had suggested that the insects were perhaps 

 migrating from one disti'ict to another, and had paused to rest 

 on the mountain-top ; but the observation on Peiialai-a threw 

 new light on the interpretation ; for these Fossors as well as 

 the Dorcadion were in a state of great activity in the bright 

 sun and were pairing freely. Furthermore, both were in 

 fresh condition and had evidently only recently emerged from 

 the pupal state. 



It was suggested as probable that certain species of insects 

 with powerful flight, after reaching the imaginal state, have 

 the instinct to seek conspicuous isolated features in the 



